1. Field of the Invention
The field of the invention is that of seismic data acquisition. More specifically, the invention relates to seismic data acquisition systems comprising a cabled network connected to a central processing unit, for example onboard a vehicle. The invention particularly relates to the seismic prospecting method for oil industry, but may be applied to any field implementing a seismic data acquisition network. However, one particular application of the invention relates to land seismic data acquisition systems.
2. Background of the Invention
Seismic data acquisition operations in the field conventionally use networks of electronic units whereto ground movement sensors are connected.
These sensors, generally referred to using the term geophones, are generally interconnected in groups of sensors by cables to form clusters referred to as “strings”. One or a plurality of these strings are connected to said electronic units. The electronic units, interconnected by a cabled digital network, perform the analogue to digital conversion of the signal from the groups of sensors and send these data to the recording truck via said digital network, a central data processing unit being onboard the truck.
Novel systems have recently been introduced on the market wherein the sensors are integrated in the electronic conversion unit, which eliminates the geophone strings. In this case, the sensors are micro-machined accelerometers.
To collect the geophysical data, one or a plurality of seismic sources in contact with the ground are activated to propagate omnidirectional seismic wave trains. The sources may among other things consist of explosives, falling weights, vibrators or air guns in marine environments.
The wave trains reflected by the layers of the subsurface are detected by the sensors, which generate an analogue signal characterising the reflection of the waves on the geological interfaces of the subsurface.